Bard MEGA-TEC W090A, Service Instructions Manual

Page: 18 / 159

Manual 2100-671C
Page 16 of 59
8 Press ENTER key to scroll to
Enable.
9. Press UP or DOWN key to change Off to On .
10. Press ENTER key to save.
The valve can also be opened or closed using the EEV
service tool (Bard Part # 2151-021). This magnetic EEV
service tool (shown in Figure 18) is used to manually
open the EEV. To do this, remove the EEV stator coil (red
color with retaining nut on top), slide the magnetic tool
over the shaft where the stator was removed and turn in
a clockwise direction to open the valve to the full open
position (directional arrows are provided on the tool).
Opening the valve to the full open position will aid in the
refrigerant reclamation and evacuation processes.
With the stator removed, the resistance should be 40
ohms +/- 10%. There are two sets of three wires that
will have this resistance.
After removing the EEV service tool, reapply the EEV
stator coil and retaining nut. Upon powering the unit
back up, the control board will automatically drive the
EEV back to the fully shut position, and then back to
the 20% open position prior to starting the compressor
back up. Once the compressor starts, the control board
will again modulate the EEV position to control the
system superheat.
System Pressures
To view system pressure and temperatures during this
process:
1. From the Status screen, press UP or DOWN key
until Quick Menu displays Unit Information icon
( ). Press ENTER key.
2. Press UP or DOWN keys to scroll to A/C Circuit 1
Info and A/C Circuit 2 Info screens (see Figure 6
A/C Circuit Measurements on page 9).
FIGURE 18
Electronic Expansion Valve (EEV) and Service Tool
EEV Service
Tool
EEV Stator
Coil
EEV
Suction Pressure Transducer
The unit has pressure transducers installed on
the suction line between the evaporator coil and
compressor (one on refrigerant circuit 1 and one on
refrigerant circuit 2). The transducer is used for system
monitoring of suction system pressures. The transducer
is used with the suction temperature sensor to provide
a real time superheat calculation that determines the
EEV position.
This transducer reading can be verified and adjusted by:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
TECHNICIAN password 1313.
3. Press UP or DOWN keys to scroll to
I/O Config
;
press ENTER key.
4. Press UP or DOWN keys to scroll to
Analog Inputs
;
press ENTER key.
5. Press UP or DOWN keys to scroll to
Analog Ins
6/19
(for circuit 1) or
Analog Ins 8/19
(for circuit
2).
6. Verify the measurement displayed on screen is
accurate (see Figure 19).
7. If the measurement needs to be adjusted, apply an
offset value by pressing ENTER to scroll to
Offset
.
8. Press UP or DOWN keys to adjust the offset.
9. The update will not take effect until the cursor is
moved out of the Offset parameter.
10. Once adjusted, press the ESCAPE key several
times to return to Main Menu screen.
FIGURE 19
Adjusting Suction Sensor/Transducer
Pressure Values
Troubleshooting the Suction Pressure Transducer
0-250 psig
-5v Nominal, .5 – 4.5v Actual
4v/250 psig = .016 volts per 1 psig
Example: 125 psig x .016 + .5 volts = 2.5 volts
Formula for Tech:
Measured Pressure x .016 + Voltage Offset = Expected
Transducer Signal Voltage (see Figure 20).